1. Field of the Invention
This invention relates to a process for the purification of raw coprolactam, in particular, of caprolactam obtained by extraction with alkylated phenols from its sulphuric solution. The present invention relates also to the caprolactam thus purified.
2. Prior Art
It is known to extract caprolactam from its sulphuric solution, with alkylated phenols, and to subsequently re-extract the caprolactam with water, from the aqueous phenol solution. The caprolactam thus obtained does not present, however, a purity degree sufficient to permit the obtention of nylon 6 of the "polymerization grade", i.e nylon 6 having the characteristics requested for the production of industrial products (fibers, plastics). Various processes are known for the purification of raw caprolactam thus obtained, whereby a product having such a purity as to be suitable as "polymerization grade" is obtained. As it is well known, these purification treatments comprise oxidizing treatments, for example with potassium permanganate, sodium hypochlorite, ozone, hydrogen peroxide and the like. In order to further increase the degree of purity of the caprolactam, vacuum distillations of the caprolactam are employed downstream of said treatments.